Movable cable loop descent system

ABSTRACT

A movable cable loop descent system comprises a cable for forming into a loop, a receiver for attachment to a structure having a receiver pulley for engaging the cable loop, a brake assembly, having a drive pulley for being rotated by the cable loop, the brake assembly for slowing a rate of travel of the cable loop and a carriage supporting a load for attachment to the cable loop at a point and for movement between the structure and the ground. A rotor and substantially parallel conductive frame is mounted on an axle through the drive pulley. Magnets on a surface of the rotor and/or the frame induce eddy currents, as they are relatively rotated, which create a rotational braking force controlling descent of the carriage and load. The brake assembly may be removably positioned by a drive-on anchor. The cable is removable and the system may form a kit.

RELATED APPLICATIONS

The present disclosure is a National Stage of International ApplicationNo. PCT/CA2011/050055, filed Feb. 1, 2011, which in turn claims priorityfrom U.S. Provisional Patent Application No. 61/300,179 entitled MovableCable Loop Descent Systems filed Feb. 1, 2010 by Gregory A. Hartman andDan S. Smith, which is incorporated by reference in its entirety herein.

TECHNICAL FIELD

The present disclosure relates to a system for controlling the descentrate of a load attached to a cable, and more particularly, to a descentsystem for controlling the rate of descent of a load affixed to andsuspended from a movable cable loop extending between a raised platformand the ground surface.

INTRODUCTION

In co-pending Canadian Patent Application No. 2,646,073 filed Dec. 9,2008 by Hartman et al (“Hartman 1”) and entitled DESCENT CONTROL DEVICE,which is incorporated by reference in its entirety herein, a magneticdescent control device is disclosed. The device provides brakingcapability to an enclosure for rapid but controlled transport ofpersonnel from an elevated structure to a ground surface a distance awayfrom the structure. The descent path of the enclosure is defined by atleast one cable extending between an upper point affixed to thestructure and a lower point affixed to the ground surface.

The device comprises a central axle affixed to a rotating driven sheaveacting as a drive assembly, which grips the cable guiding the descentpath of a body carrying cage. The central axle has a shoulder upon whichrests a rotor. The rotor is encased within a front and back frame ofconductive material. Disposed along at least one surface of the rotor orat least one of the conductors or both, is a series of magnets such thatrotation of the rotor relative to the conductors creates relative motionbetween the magnets' magnetic field and the conductor and induces eddycurrents in the conductor that oppose the magnetic field and create arotational braking force. As a result, precise and controllable descentof the enclosure may be obtained with little or no mechanical wear orrisk of overheating.

Each device is mounted on an inner surface of a side wall of theenclosure with the central axle passing through the side wall and beingdriven by a driven sheave in contact with the cable on the outer surfaceof the side wall. Hartman 1 discloses using a plurality of such devicesto drive assemblies contacting a common cable and using at least twocables one on either side of the enclosure. The devices on each side ofthe enclosure are supported by a plurality of adjacent idler sheaves toimpart tension to the cable where the driven sheaves engage it.

As a result of the foregoing, the minimum size, structure andcomposition of the side walls of the enclosure are constrained in thatthey are sufficiently large and rigid to support three or four sheavesthereon.

Since the devices pass through the side wall of the enclosure, which ismaintained in a generally vertical orientation for the safe transport ofpersonnel, the steepness of the angle of descent of the enclosure isalso somewhat constrained, which imposes limitations on the positioningof the cable both at the elevated structure end and at the groundsurface, especially given that at least two cables are used. Moreover,considerable site preparation may be called for to ensure that thereremains clearance along the descent path for both the cable and theenclosure.

In co-pending U.S. patent application Ser. No. 12/617,999 filed Nov. 13,2009 by Hartman et al (“Hartman 2”) and entitled SINGLE CABLE DESCENTCONTROL DEVICE, which is incorporated by reference in its entiretyherein, a single cable descent control device is disclosed. It comprisesa rotor with corresponding frames of conductive material mounted on acommon central axle on either side of a drive pulley. The pulley isadapted to sit above a single descent cable. A load is suspended fromthe device. Disposed along at least one surface of the rotor or of thecorresponding frames or both, is a series of magnets such that rotationof the rotor relative to the frames induces eddy currents that opposethe magnetic field and create a rotational braking force providingprecise and controllable descent of the enclosure with little or nomechanical wear or risk of overheating.

In this configuration, constraints on the side of the enclosure aredispensed with, as are corresponding limitations on the positioning andangle of descent of the cable. Further, significant labor and materialsavings in manufacturing the enclosure may be obtained from theresulting simplicity of design. The device may be used in numerous otherapplications, including without limitation, permitting controlleddescent of gondolas or chairs from ski lift operations when normal liftoperation is temporarily precluded.

Nevertheless, in both of these embodiments, the cable is fixed, in someexample embodiments, permanently, to both the structure at the upperpoint and the ground surface at the lower point, under tension.Furthermore, because the brake forms part of the descending device,considerable effort is expended in raising the device, including theenclosure and the movable brake, from the ground surface to thestructure after each use of the device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a brake side view drawing showing an example embodiment of amovable cable loop descent system according to the present disclosure;

FIG. 2 is a brake side view of an example embodiment of a receiver,carriage and cable loop of the movable cable loop descent system of FIG.1;

FIG. 3 is a pulley side view drawing of an example embodiment of a brakeassembly and cable loop of the movable cable loop descent system of FIG.1;

FIG. 4 is a brake side view drawing of the brake assembly of FIG. 3;

FIG. 5 is an expanded view of the tensioning mechanism of the brakeassembly of FIG. 4;

FIG. 6 is a pulley side perspective view drawing of the brake assemblyof FIG. 3;

FIG. 7 is a front view drawing of the brake assembly of FIG. 4 withcover and cable loop removed;

FIG. 8 is a rear cross-sectional view of the brake mechanism of theexample embodiment of FIG. 3; and

FIG. 9 is a plan view of an example embodiment of a rotor for use in thebrake mechanism of the example embodiment of FIG. 8.

Like reference numerals are used in the drawings to denote like elementsand features.

DESCRIPTION

The present disclosure provides an example embodiment of a movable cableloop descent system. Such descent system comprises a cable for forminginto a loop, a receiver for attachment to a structure at an initialpoint, having a receiver pulley for engaging the cable loop around it, abrake assembly at a terminal point, having a drive pulley for engagingand being rotated by the cable loop, the brake assembly for slowing arate of travel of the cable loop around the pulleys and a carriage forattachment to the cable loop at a point, for supporting a load and formovement between the initial point and the terminal point as the cableloop travels around the pulleys.

In some example embodiments, the drive pulley, the receiver pulley andthe cable loop define and lie substantially in a common plane.

In some example embodiments, the receiver comprises a freely rotatablepulley about which the cable loop may be placed. In some exampleembodiments, the carriage may be removably secured to the receiver in aready position to maintain the carriage proximate to the structure andavailable for use. In some example embodiments, the receiver comprises amagnet in a seat configured to engage a metal spigot of the carriage.The imposition of a load at the carriage causes the carriage to separatefrom the receiver and commence its descent along a path defined by adownstream portion of the cable loop. In some example embodiments, thereceiver may be removably attached to a mounting bracket for affixingthe receiver to the structure.

In some example embodiments, a plurality of idler sheaves inhibits slipbetween the cable loop and the drive pulley when under tension. In someexample embodiments, the drive pulley and idler sheaves are mounted on acommon plate which is adapted to pivot about a pivot point in a planedefined by the drive pulley in order to permit the cable loop to remainunder a desired tension between the brake assembly and the receiver. Insome example embodiments a tension indicator is provided for calibrationpurposes.

In some example embodiments, a rotor with a corresponding frame ofsubstantially parallel conductive material is mounted on a transverseaxle about which the drive pulley is rotatable. In some exampleembodiments, a series of magnets is disposed along at least one surfaceof the rotor or of the corresponding frame or both, such that rotationof the rotor in response to rotation of the drive pulley relative to theframe induces eddy currents that oppose the magnetic field and create arotational braking force providing precise and controllable descent ofthe carriage and its supported load, with little or no mechanical wearor risk of overheating.

In some example embodiments, one of a plurality of co-axial drivepulleys of different diameter may be employed to vary the rate ofrotation of the rotor relative to the rate of travel of the cable loopand thus adjust the applied braking force. In some example embodiments,the at least one idler sheave may have corresponding co-axial sheaves.

In some example embodiments, the brake assembly may be removably fixedin position by means of a drive-on anchor. In some example embodiments,minor positional adjustments may be made to the brake assembly relativeto the drive-on anchor for purposes of maintaining a desired tension onthe cable loop. In some example embodiments, a rotatable wheel crank maybe employed to adjust the position of the brake assembly relative to thedrive-on anchor.

In some example embodiments, the carriage accepts within it the cableloop at two places. The carriage is constrained to engage the cable loopand inhibit travel of the cable loop relative to a first place. In someexample embodiments, the first place is proximate to where eyelets atopposing ends of the cable are joined together to form the cable loop.In some example embodiments, the first place is at a portion of thecable substantially between an eyelet at a first end of the cable and acable grommet or cable clamp disposed on the cable and separated fromthe eyelet by a short distance. In some example embodiments, a cablegrommet is placed at the same separation from the eyelet at each end ofthe cable. In some example embodiments, the second place issubstantially vertically disposed from the first place on an oppositeportion of the loop. In some example embodiments, the carriage permitssubstantially free travel of the cable loop at the second place. In someexample embodiments, a secondary brake lever may be engaged duringdescent, causing a secondary brake to be driven against the cable loopat the second place and inhibiting travel of the cable loop relative tothe second place.

As the carriage is constrained to engage the cable loop substantially atthe first place and the cable loop is freely movable between thereceiver and the brake assembly, under load, the carriage causes thecable loop to travel relative to the pulleys in the receiver and thebrake assembly, causing the carriage to descend toward the groundsurface. The rate of descent is constrained because the travel of thecable loop about the drive pulley causes the drive pulley andconcomitantly the rotor to rotate, creating eddy currents that create arotational braking force to slow the descent of the carriage incontrolled fashion.

In some example embodiments, the load may comprise personnel orequipment or both suspended from a gripping portion such as a T-handle.The increase in load on the carriage causes the carriage to separatefrom the receiver and descend from the structure to the ground surfacealong the path defined by the cable loop.

The brake assembly is physically separated from the carriage, forexample at ground level at or proximate to a low end of the cable loop.This permits the load to be borne by the carriage to be substantiallyrestricted to the person or equipment being evacuated from the elevatedstructure. Additionally, this permits the carriage to have a compactsize, be lightweight and be composed of a minimum of material, which inturn provides attendant benefits in terms of set-up, maintenance andoperation. For example, the receiver may only restrain the carriage inthe ready position with a small magnet, which is easily displaceablewith the application of a small load on the carriage. Additionally, thepath defined by the cable loop may be quickly reconfigured, by movingthe position of the receiver relative to the elevated structure, bymoving the position of the brake assembly along the ground surface orboth. Further, separating the carriage from the brake assembly mayreduce time, effort and expense of returning the carriage to the readyposition proximate to the receiver after use. Still further, positioningthe brake assembly at ground level may facilitate service and repair ofthe brake assembly.

The present disclosure may provide in some example embodiments a kitcomprising a cable for forming into a loop, a receiver having a receiverpulley for engaging the cable loop around it at an initial point, abrake assembly having a drive pulley for engaging and being rotated bythe cable loop at a terminal point, the brake assembly for slowing arate of travel of the cable loop around the pulleys; and a carriage forsecuring to the cable and for supporting a load for movement between theinitial point and the terminal point as the cable loop travels aroundthe pulleys.

Reference is now made to FIG. 1, which illustrates a movable cable loopdescent system 100. The descent system 100 comprises a receiver 110 formounting to a structure 10, such as a monkey board or derrick, at anelevated point 11; a brake assembly 120, for positioning on or slightlyabove a ground surface 20 away from the structure 10; a cable 130 forforming into a loop 131 extending between the receiver 110 and the brakeassembly 120 and a carriage 140 for attachment at a point along thecable loop 131 for transporting a load (not shown) between the receiver110 and the brake assembly 120.

Referring now to FIG. 2, the receiver 110 comprises a receiver mount 210and a receiver housing 220.

The receiver mount 210 comprises a securement portion 211 and a bracket212. The securement portion 211 permits the receiver 110 to be securelyfastened to the structure 10 at the elevated point 11. In some exampleembodiments, the securement portion 211 of the receiver mount 210 may beclamped by bolts 213 to a beam or other structural element 12 of thestructure 10. The nature of the securement portion 211 of the receivermount 210 may be adapted to engage a particular configuration of thestructure 10 to which the receiver mount 210 is to be secured.

By way of non-limiting illustration only, in the example embodimentshown in FIG. 2, the securement portion 211 comprises a pair of L-shapedmembers 214 secured at one end by bolts 215. The members 214 may bepositioned on either side of the structural element 12 of the structure10 and secured thereto by the bolts 215. The members 214 may in someexample embodiments be composed of steel.

The bracket 212 extends away from the structure 10 when the receivermount 210 is secured thereto and permits the receiver housing 220 to bepivotally mounted to the receiver mount 210. By way of non-limitingillustration only, in the example embodiment shown in FIG. 2, thebracket 212 comprises a pair of protrusions 216, 217 each having acomplementary and coaxial bore 218 passing transversely therethrough.The protrusions 216, 217 are spaced apart to accommodate a tongue 221 ofthe receiver housing 220 to pass between them. The protrusions 216, 217may in some example embodiments be composed of steel cast with or insome example embodiments welded in position against a face of the member213.

A bolt 219 passes through the bores 218 in each of the protrusions 216,217 and through a complementary bore 225 of the tongue 221 of thereceiver housing 220 to permit the receiver housing 220 to pivot along aplane relative to the receiver mount 210. In some example embodiments,the receiver mount 210 is secured to the structure 10 in an orientationsuch that the plane along which the receiver housing 220 may pivot issubstantially horizontal, to accommodate positioning the brake assembly120 laterally relative to the orientation of the receiver mount 210 asmounted on the structure 10.

The receiver housing 220 comprises a tongue 221, a pulley housing 222,the receiver pulley 223 and a receiver seat 224. The pulley housing 222extends between the tongue 221 and the receiver seat 224. In someexample embodiments, the tongue 221, pulley housing 222 and receiverseat 224 may be composed of steel. In some example embodiments, thetongue 221, pulley housing 222 and receiver seat 224 may be integrallyformed. In some example embodiments, the pulley housing 222 and receiverseat 224 may be integrally formed and the tongue 221 welded thereto.

The tongue 221 has an internal bore 225 passing therethrough toaccommodate the bolt 219 when positioned between the protrusions 216,217 of the bracket 212 of the receiver mount 210.

The pulley housing 222 is a substantially circular portion of thereceiver 220 within which the receiver pulley 223 may be seated. Ahinged cover 226 opens to permit the receiver pulley 223 to be removed,for example, to permit the cable loop 131 to be wound around it. By wayof non-limiting illustration, the example embodiment disclosed in FIG. 2shows the cover 226 extending over the top (when in an operationalconfiguration) of the pulley housing 222 so that the receiver pulley 223may be inserted from above and seated within the pulley housing 222. Inthis fashion, once the receiver pulley 223 has been inserted into thepulley housing 222, the cover 226 may be closed to substantially protectthe receiver pulley 223 from the elements and to secure the receiverpulley 223. In some example embodiments, the cover 226 may be composedof steel.

The pulley housing 222 accepts and supports an axle 227 of the receiverpulley 223. In some example embodiments, the pulley housing 222comprises a pair of slots 228 extending from the cover 226 to anintermediate point at which the axle 227 is in operational position, toguide the axle 227 while the receiver pulley 223 is moved into positionwithin the pulley housing 222. If, as in the non-limiting exampleembodiment illustrated in FIG. 2, the cover 226 extends from the top ofthe pulley housing, the axle 227 will be drawn to and tend to remain inthe operational position by gravity. In other example embodiments, amechanism to retain the axle 227 in the operational position againstgravity, such as providing narrow shoulders (not shown) in the slots228, may be appropriate.

A portion of the pulley housing 222 remains open to permit entry andexit of the cable loop 131 wound around the receiver pulley 223 when inposition within the pulley housing 222. By way of non-limitingillustration, in the example embodiment shown in FIG. 2, the pulleyhousing 222 comprises a pair of parallel plates to accommodate the slots228 and to substantially cover the faces of the receiver pulley 223,while remaining open along approximately half of its circularcircumference to accommodate the entry and exit of the cable loop 131.In some example embodiments, slots or bores (not shown) in a closedcircumferential surface (not shown) of the pulley housing 222 mayprovide similar access for entry and access. Such an alternativeembodiment may further protect the receiver pulley 223, when seated inposition within the pulley housing 222 from the elements, but may causewear on the cable loop 131 as it is rotated about the receiver pulley223, if the cable loop 131 comes into contact with the edges of any ofthe slots or bores.

The receiver pulley 223 is a pulley having a transverse axle 227 aboutwhich it is substantially freely rotatable. It is removable from thereceiver housing 120 by opening the cover 226. Once removed, the cableloop 131 may be wound about the circumference of the receiver pulley 223not under tension and then re-inserted into the pulley housing 222.

In some example embodiments, a groove (not shown) extends along thecircumferential edge of the receiver pulley 223. In some exampleembodiments, the groove may be semi-circular in shape and sized toaccept the cable loop 131 in a traction fit and so as to displace anydebris that may have built up on the cable loop 131 such as snow, ice,grease, dirt, wax or the like.

In some example embodiments, the axle 227 is sized to slide within theslots 228 of the pulley housing 222 when inserting or removing thereceiver pulley 223. In some example embodiments, once in operationalposition seated within the pulley housing 222, the axle 227 may besecured by nuts (not shown) or other appropriate mechanism. The receiverpulley 223 may be additionally secured within the pulley housing 222 byclosing and securing the cover 226. Once the cover 226 has been closedand secured, the likelihood of the cable loop 131 slipping off thereceiver pulley 223 is substantially minimized, especially with theprovision of the circumferential groove.

The receiver seat 224 extends from the pulley housing 222 on the otherside from the receiver mount 221. It is adapted to engage the carriage140 in position proximate to the structure 10 until a load, such aspersonnel seeking to escape the structure, or equipment, or both, thatexceeds a predetermined threshold, is applied to the carriage 140. Oncesuch a load is applied, the carriage 140 is undocked from the receiverseat 224 and follow the path of the cable loop 131 downward toward theground surface 20 near the braking assembly 120.

By way of non-limiting illustration, in the example embodiment shown inFIG. 2, the receiver seat 224 comprises a receptacle 231 and a channeldefined by a pair of wings 232 extending from the receptacle 231 awayfrom the pulley housing 222. The receptable 231 is adapted toaccommodate and retain a spigot 146 of the carriage 140 in a readyposition proximate to the structure 10 to provide a mechanism for rapidegress from the structure 10 for personnel or equipment or both. In someexample embodiments, the spigot 146 is composed of ferromagneticmaterial and the receptable 231 houses a magnet 233 to magneticallyengage the spigot 146 to maintain the carriage 140 in the readyposition. The threshold load beyond which the carriage 140 may bereleased from the receiver seat 224 may be set by the magnetic fieldstrength of the magnet 233 imposed upon the spigot 146.

The wings 232 serve to guide the carriage 140 away from the receiver120. In some example embodiments, the wings 232 may have a slightlydiverging profile to facilitate returning the carriage 140 to the readyposition within the receiver seat 224 after use.

The receiver 110 secures the carriage 140 until a load (not shown), suchas personnel or equipment or both is applied to the carriage, causing itto be released from the receiver 110 and to descend in controlledfashion along the path defined by the cable loop 131 to the ground 20proximate to the brake assembly 120.

Turning now to FIG. 3, there is shown a side view of the brake assembly120 viewed from the pulley side. The brake assembly 120 comprises aframe 310, an anchor 320, a brake mount 330, a drive pulley subsystem350 and a brake 360 (FIG. 4).

The frame 310 is an open framework that substantially encloses andprotects the rest of the brake assembly 120. By way of non-limitingillustration, in the example embodiment of FIG. 3, it comprises a pairof substantially rectangular sides 311, spaced apart by a plurality ofcross beams 312 each comprising a segment of substantially equal length,secured thereto.

The substantially open nature of the frame 310 permits the cable loop131 to enter and exit the brake assembly 120 from a wide variety ofangles (corresponding to a wide variety of points 11 of differentelevations where the receiver 110 is mounted to the structure 10) andpermits the anchor 320 to extend from the frame 310 substantiallywithout interference.

In some example embodiments, the sides 311 and cross beams 312 of theframe 310 may be composed of tubular steel. In some example embodiments,the sides 311 and cross beams 312 are welded together. In some exampleembodiments, the corners of the sides 311 may be rounded.

In some example embodiments, a tubular mount 313 is secured to the topof a plurality of cross beams 312 mounted to the bottom of the frame 310and is adapted to accept a tubular tongue 322 of the anchor 320 in orderto secure the frame 310 in position. Corresponding bores 314 on opposedsides of the mount 313 accept a pin 315 that may pass through them and acorresponding one of a number of bores 326 in the tongue 322 to securethe brake assembly 120 roughly in position relative to the anchor 320.

In some example embodiments, the mount 313 is composed of steel. In someexample embodiments, the mount 313 is welded to the cross beams 312.

As shown by way of non-limiting illustration in FIG. 6, in some exampleembodiments, the mount 313 has secured thereon a toothed rotatable gear316 to engage tooth-shaped indentations 327 in the tongue 322 of theanchor 320, so as to permit fine adjustment of the position of the brakeassembly 120 relative to the structure 10 and to permit fine adjustmentof the tension in the cable loop 131 extending between the brakeassembly 120 and the receiver 110 secured to the structure 10. In someexample embodiments, a wheeled crank 328 extends substantially upwardlyfrom the gear 316 to permit easily rotation of the gear 316.

The anchor 320 and comprises a ground surface engaging pad 321 and anadjustable tongue 322. The pad 321 may be substantially planar having aground-engaging surface 323. In some example embodiments, theground-engaging surface 323 may comprise a plurality ofdownwardly-extending spikes 329 to engage the ground surface 20,including turf, snow or ice.

The pad 321 may be secured in place by driving a wheel of a vehicle suchas a truck, over the pad 321 in a direction transverse to the directionof extension of the tongue 322, anchoring the pad 321 in place in aground-engaging fashion by applying a downward force onto the pad 321.In some example embodiments, the pad 321 may comprise a plurality ofvertical ridges to constrain the wheel to approach the pad in thetransverse direction.

In some example embodiments, the pad 321 may contain a plurality ofspring-loaded louvers 324 (FIG. 6), which constrain the wheel toapproach the pad 321 from an initial direction and proceed in the samedirection to exit the pad 321. Additionally, the louvers 324 providesome transverse stability to restrict the ability of the wheel fromsliding off in the opposite direction. In some example embodiments, atleast one louver 324 may be oriented in an opposing direction torestrict the ability of the wheel from unintentionally departing the pad321 in either transverse direction. When the wheel is to depart the pad321, the opposed louver 324 may be depressed manually to permit thewheel to drive over it and depart the pad 321.

The pad 321 may be configured to accept the tongue 322. In some exampleembodiments, a bracket 325 extends above the pad 321 and is adapted tosecure the tongue 322 to the pad 321. In some example embodiments, thetongue 322 is secured in a pivoting manner to the bracket 325.

In some example embodiments, the pad 321 is composed of steel.

The tongue 322 comprises an elongate member which may be accepted by themount 313 in a sliding fit. The tongue 322 comprises a plurality ofspaced-apart bores 326 along its length adapted to accept the insertionof the pin 315 therethrough to secure the tongue 322 to the mount 313 tomaintain the brake assembly 320 roughly in position relative to thestructure 10. As shown by way of non-limiting illustration, in theexample embodiment of FIG. 3, the tongue 322 is composed of tubularsteel.

As shown by way of non-limiting illustration in FIG. 3, the tongue 322may comprise a regular tooth pattern of indentations 327 adapted toengage the teeth of the gear 316 (FIG. 6) secured to the mount 313 ofthe frame 310, to permit fine adjustment of the position of the brakeassembly 120 relative to the structure 10 and to permit fine adjustmentof the tension in the cable loop 131 extending between the brakeassembly 120 and the receiver 110 secured to the structure 10.

As may be better seen in FIGS. 3 through 5, the brake mount 330comprises a base 331, at least one pivot plate 332 and a tensioner 333.The base 331 extends substantially vertically from the mount 313 andextends, in a substantially vertical plane, to engage in parallelfashion, the at least one pivot plates 332. Further, tensioner 333 issecured to the base 331 as described below.

Base 331 comprises a protrusion at a distal end from the mount 313,through which a transverse bore 334 passes. The transverse bore 334 issized to accommodate a pivot bolt 335 passing through the at least onepivot plate 332 and the base 331. In some example embodiments, there aretwo pivot plates 332 and each is disposed to one side of the base 331.The at least one pivot plates 332 and the base 331 are secured togetherby the pivot bolt 335 and a complementary nut (not shown).

By way of non-limiting illustration, in the example embodiment of FIG.5, base 331 may have a partial bore 337 in an end (in a direction facingthe structure 10, which, for illustration, is designated as the frontend) to accommodate insertion and securement therein of the tensioner333. In some example embodiments, the partial bore 337 is threaded toengage a bolt 346 of the tensioner 333.

In some example embodiments, the base 331 may have a grid of markings338 on at least one side, extending beyond the corresponding pivot plate332, which acts as a scale indicating a tension setting applied to thecable loop 131 by adjustment of the tensioner 333 as discussed below.

In some example embodiments, the base 331 is composed of steel. In someexample embodiments, the base 331 is welded to a top surface of themount 313.

Each pivot plate 332 is a planar plate having first 338 and secondfingers 339 at one extremity thereof. At another extremity thereof, aprotrusion 340 extends outwardly in the plane of the pivot plate 332,which cooperates with the grid of markings 338 to indicate the tensionsetting applied to the cable loop 131. Between the second finger 339 andthe protrusion 340 lies a shelf 341.

The first finger 338 has an offset bore 342 passing through it. Theoffset bore 342 is sized to accommodate a pulley bolt 343 passingthrough it and a pulley plate 351 of the drive pulley subsystem 350 tosecure the pulley plate 351 to the pivot plate 332. The second finger339 provides a support offset from the first finger 338 against which anedge of the pulley plate 351 may rest.

In addition to the offset bore 342, the pivot plate 332 has a centralbore 344 passing substantially through its centroid. The pivot plate 332is secured by bolt 335 and nut 336 passing through the central bore 344and through the bore 334 of the base 331. Despite being so secured, thepivot plate 332 may pivot slightly relative to the base 331 as tensionis applied to it by the cable loop 131 wound around the drive pulley 352of the drive pulley subsystem 350.

The shelf 341 provides a surface against which the tensioner 333 mayrest.

Between the protrusion 340 and the first finger 338, a blocking bore 345is positioned near an edge of the pivot plate 332. The blocking bore 345is sized to accommodate a crosspiece 349 that interconnects each of theat least one pivot plates 332 positioned on either side of the base 331.The crosspiece 349 restricts the extent to which the pivot plates 332may pivot forward relative to the base 331. In some example embodiments,the bores 345 extend partially through the pivot plate 332 and thecrosspiece 349 is secured in position by bolt 335 and nut 336 pullingthe pivot plates 332 together against each side of the base 331. In someexample embodiments, the bores 345 extend completely through the pivotplate 332 and the crosspiece 349 is secured by a nut (not shown)tightened against threaded ends of the crosspiece 349. In some exampleembodiments, the blocking bores 345 are internally threaded, permittingthe threaded ends of the crosspiece 349 to be secured thereto.

In some example embodiments, each of the pivot plates 332 may becomposed of steel.

As may be better seen in FIG. 5, the tensioner 333 comprises a bolt 346,a washer 347 and a biasing element 348, such as a spring. The bolt 346is sized to be accommodated within the partial bore 337, with thebiasing element 348 positioned, such as by surrounding the threadedportion of the bolt 346, between the head of the bolt 346 and the mount331. In some example embodiments, the bolt 346 is secured by engagingthe interior threads of the partial bore 337. The washer 347 ispositioned around the threaded portion of the bolt 346, interposedbetween the biasing element 348 and the head of the bolt 346. The headof the bolt 346 and the washer 347 rest on the shelf 341. Thus, as thebolt 346 is tightened, the biasing element 348 compresses between thewasher 347 and the mount 331. The tensioner 333 serves to calibrate thegrid of markings 338 to the applied tension of the cable loop 131. Insome example embodiments, once so calibrated, other than periodic orintermittent adjustments from time to time, the tensioner 333 is notfurther adjusted.

Rather, as the anchor 320 is positioned relative to the structure 10,coarsely adjusted by selecting a bore 326 of the tongue 322 at which tosecure the mount 313 and/or finely adjusted by using the gear 316against the indentations 327, the pivot plates 332 are forced rearwardlyof the mount 331, causing the pulley plate 351 to be rotate lower, thusincreasing the tension applied to the cable loop 131 wound around thedrive pulley 352 and the receiver pulley 223. A relative indication ofthe tension applied to the cable loop 131 is provided by the position ofthe protrusion 340 relative to the grid of markings 338 as the pivotplates 332 are forced rearwardly.

As may be better seen in FIGS. 3 and 5, the drive pulley subsystem 350comprises a pulley plate 351, a drive pulley 352, at least one idlersheave 353, a transverse axle 354 and a cover 651 (FIG. 6). The drivepulley 352 is positioned at an intermediate point of the pulley plate351 and on one side thereof.

The at least one idler sheave 353 is positioned on the same side of thepulley plate 351 as the drive pulley 352 and forward of the drive pulley352, so that the drive pulley 352 lies between the at least one idlersheave 353 and the pivot plate 332.

The pulley plate 351 is a substantially planar plate having a transversebore 355 sized to accommodate the transverse axle 354 driven by thedrive pulley 352 to engage and drive the rotor 362 of the brake 360 onthe other side of the pulley plate 351.

The pulley plate 351 is sandwiched between the at least one pivot plates332 above the mount 331 and secured to the at least one pivot plates 332by the pulley bolt 343. In some example embodiments, the pulley plate351 may be composed of 6061-T6 aluminum, or steel, especially if magnets366 are positioned on the face opposite the face upon which the drivepulley 352 is mounted, as discussed below in connection with the brake360. In some example embodiments, such opposite face of the pulley plate351 may be cladded or inserted with a material such as copper so as toalter the patterns or intensity or both of eddy currents induced thereinby operation of the brake 360 as described below.

The drive pulley 352 is a pulley rotatable about and in fixed rotationalengagement with the transverse axle 354. In some example embodiments, atthe centre of the drive pulley 352, a key 357 is cut to accept thetransverse axle 354 and one of the at least one shoulders 356 (FIG. 6)situated thereon in such a manner to maintain the drive pulley 352 is infixed rotational engagement with the axle 354.

In some example embodiments, a groove 852 (FIG. 8) extends along thecircumferential edge of the drive pulley 352. In some exampleembodiments, the groove 752 may be semi-circular in shape and sized toaccept the cable loop 131 in a traction fit and so as to displace anydebris that may have built up on the cable loop 131 such as snow, ice,grease, dirt, wax or the like.

To further assist in the removal or snow, ice, grease, dirt, wax or thelike, and to increase heat dissipation when the cable loop 131 movesthrough the circumferential groove (not shown), the drive pulley 352 mayin some example embodiments include a series of channel bores (notshown) extending parallel to the axis of rotation near thecircumferential end surface of the drive pulley 352.

As may be better seen in FIG. 8, in some example embodiments, the drivepulley 352 comprises a pair of adjacent coaxial pulleys of differingdiameter. In some example embodiments, the pulley of greater diameter358 lies between the pulley plate 351 and the pulley of lesser diameter359. The different diameter pulleys 358, 359 may be employed to cover awide range of angles of descent of the carriage and minimize the amountof tension adjustment employed.

This is because as the angle of descent is increased, a greater brakingforce is called for, as discussed below. By reducing the size of thedrive pulley 352, for a given rate of descent, the rotational rate ofthe drive pulley 352 and thus the rotor 362 increases, creating anoffsetting increased braking force. To some degree, the angle of descentis correlated to the elevation of the receiver 110. Thus, by way ofnon-limiting example, a pulley 359 of the drive pulley 352 having adiameter of 5.5 inches may be suitable for elevations of the receiver110 of substantially between 10 and 30 meters, while a pulley 358 of thedrive pulley 352 having a diameter of 8 inches may be suitable forelevations of the receiver 110 of substantially between 8 and 10 meters.

The at least one idler sheave 353 is mounted on the same side of thepulley plate 351 as the drive pulley 352. In some example embodiments, agroove 753 (FIG. 7) extends along the circumferential edge of the atleast one idler sheave 353, which is sized to accommodate the cable loop131 therewithin.

In some example embodiments, the groove 753 may be semi-circular inshape and sized to accept the cable loop 131 in a traction fit and so asto displace any debris that may have built up on the cable loop 131 suchas snow, ice, grease, dirt, wax or the like.

To further assist in the removal or snow, ice, grease, dirt, wax or thelike, and to increase heat dissipation when the cable loop 131 movesthrough the circumferential groove 753, the at least one idler sheave353 may in some example embodiments include a series of channel bores(not shown) extending parallel to the axis of rotation near thecircumferential end surface of the at least one idler sheave 353.

The cable loop 131 is not wound about the at least one idler sheave 353.Rather, each idler sheave 353 applies pressure to the cable loop 131 toinhibit slip between the cable loop 131 and the drive pulley 352 whenunder tension and to facilitate rotation of the cable loop 131 (underload of the carriage 140 and any personnel or equipment or bothsuspended from it) driving rotation of the drive pulley 352 andconcomitantly the transverse axle 354 in order to drive rotation of therotor 362 in order to control or slow or both descent of the carriage140 from the receiver 110 toward the brake assembly 120.

In some example embodiments, the idler sheave 353 comprises a pair ofadjacent coaxial sheaves 758, 759 (FIG. 7), which lie substantially in acommon plane with the pulleys 358,359 respectively. As opposed to thepulleys 358,359, the adjacent sheaves 758, 759 may not be of differentdiameter, although in some example embodiments, they may be of differentdiameter. In some example embodiments, the sheave 758 corresponding tothe pulley of greater diameter 358 may be of lesser diameter than thesheave 759 corresponding to the pulley of lesser diameter 359.

With the cable loop 131 wound around the circumference of the drivepulley 352, and with pressure being applied to the cable loop 131 by theoperation of the at least one idler sheave 353, when the cover 651 is inplace, the likelihood of the cable loop 131 slipping off the drivepulley 352 is substantially minimized, especially with the provision ofthe circumferential groove 752.

The transverse axle 354 is a substantially elongate axle ofsubstantially circular cross-section. In some example embodiments, inorder to permit the axle 354 to be rotated by rotation of the drivepulley 352 and to concomitantly drive rotation of the rotor 362, withoutbeing significantly hampered by the transverse bore 355 in the pulleyplate 352, the axle 354 may comprise at least one shoulder 356 thatextends radially outward along a portion of the surface of the axle 355,corresponding to the position along the axle 354 about which the drivepulley 352 or the rotor 362 or both may be mounted, to mate withcorresponding keys 357, 367 in the drive pulley 352 or the rotor 362 orboth. In some example embodiments, the at least one shoulder 356terminates before the position along the axle 354 about which the pulleyplate 351 is positioned, so as to permit substantially free rotationwithin the transverse bore 355 of the pulley plate 351.

The brake 360 comprises a back cover 361 and at least one rotor 362 andextends on a side of the pulley plate 351 opposite to the drive pulley352 and the at least one idler sheave 353.

The back cover 361 engages the pulley plate 351 to form a conductivecavity region. In some example embodiments, the back cover 361 issecured to the pulley plate 351 at points radially distal from theenclosed rotor 362 to form a frame of substantially parallel conductivematerial around the rotor 362. In some example embodiments, the pointsof contact between the back cover 361 and the pulley plate 351 mayinclude a double lip seal installed on the pulley plate 351 to keepcontaminants away from the cavity region.

The back cover 361 is formed of a conductive material, which in someexample embodiments may be 6061-T6 aluminum, or steel, especially ifmagnets 366 are positioned on the interior face of the back cover 361,as discussed below. In some example embodiments, the interior face ofthe back cover 361 may be cladded or inserted with a material such ascopper so as to alter the pattern or intensity or both of the eddycurrents induced therein by operation of the brake 360 as describedbelow.

The back cover 361 is formed in a shape to enclose and to accept adistal end of the transverse axle 354 and the rotor 362 mounted thereonwithout contacting any part of the rotor 362.

The cavity region defined by the back cover 361 and the pulley plate 351accommodates the rotor 362 lying in a plane substantially parallel tothe plane of the pulley plate 351 and substantially normal to the axisof the transverse axle 354 passing through the transverse bore 355 ofthe pulley plate 351, without the rotor 362 contacting either the pulleyplate 351 or the back cover 361, so as to permit free rotation of therotor 362 relative to the pulley plate 351 and the back cover 361. Therotation of the rotor 362 relative to the pulley plate 351 and the backcover 361 induces eddy currents in either or both of the pulley plate351 and the back cover 361 which serve to impart a braking force to therotation of the drive pulley 352 through the transverse axle 354 andconcomitantly to the carriage 140 secured to the cable loop 131 andbearing a load comprising personnel or cargo or both.

A flange bearing 363 positioned about the transverse axle 354 betweenthe rotor 362 and the drive pulley 352 secures the axial position of thepulley plate 351 relative to the transverse axle 354 withoutsubstantially impeding rotational movement of the axle 354 relative tothe pulley plate 351 and serves as a spacer maintaining spacing betweenthe rotor 362 and the pulley plate 351 and maintaining the rotor 362 ina plane substantially parallel to the pulley plate 351. The flangebearing 363 may comprise a ball bearing, bushing, spacer, sleeve,coupling or other such element or a combination of one or more of suchelements. In some example embodiments, one or more of the flangebearings 363 is a ball bearing.

The back cover 361 may be secured in position relative to the transverseaxle 354 on the other side of the rotor 362 by a back bearing 364positioned about the axle 354, without substantially impeding rotationalmovement of the axle 354 relative to the back cover 361. Additionally,the back bearing 364 serves as a spacer maintaining spacing between therotor 362 and the back cover 361 and maintaining the rotor 362 in aplane substantially parallel to the back cover 361. The back bearing 364may comprise a ball bearing, bushing, spacer, sleeve, coupling or othersuch element or a combination of one or more of such elements.

In some example embodiments, one or more of the back bearings 363 is aball bearing. In some example embodiments, the flange bearing 363 andback bearing 364 cooperate, in some example by one contacting an innerrace of the other, to support the rotor 362 in an orientationsubstantially normal to the transverse axle 354 and substantiallyparallel to the planes of the pulley plate 351 or back cover 361 orboth.

Turning now to FIGS. 4 and 9, an example embodiment of the rotor 362 isdescribed. The rotor 362 is a cylindrical disk with a key-shaped bore367 to accommodate the transverse axle 354 in fixed rotationalengagement.

The rotor 362 is proximate to and spaced apart from the pulley plate 351by the flange bearing 363 and proximate to and spaced apart from theback cover 361 by the back bearing 364.

In some example embodiments, the surface of the rotor 362 may be spacedsubstantially 0.040″ from the pulley plate 351. In some exampleembodiments, the surface of the rotor 362 may be spaced substantiallythe same or a similar distance from the back cover 361.

In some example embodiments, the rotor 362 is composed of ferromagneticsteel. Alternatively, the rotor 362 may be composed of aluminum, copper,laminated steel, and copper or plastic, especially if the pulley plate351 or the back cover 361 or both house the magnets 366, as opposed tothe rotor 362, as discussed below.

The rotor 362 includes, in some example embodiments, a plurality ofrecesses 365 on one or the other side or both of the rotor 362, which insome example embodiments may be in an identical or similar pattern.

Each recess 365 receives a magnet 366 having axial magnetization. Themagnets 366 are mounted in a parallel magnetic pole orientation in sucha configuration that forms several distinct regions of polarity on therotor 362. In some example embodiments, the configuration is such thatthe main flux exiting the rotor 362 is of a common polarity. In someexample embodiments, the recesses 365 are laid out in at least oneconcentric ring of recesses 365 on at least one side thereof. In someexample embodiments, the recesses 365 may pass entirely through therotor 362 and the magnets 366 may be mounted therein so as to extendpartly through the rotor 362 on either side thereof.

In some example embodiments, each recess 365 may be substantially ¾″ indiameter and substantially ⅛″ deep to receive a Neodymium rare earth orother fixed magnet. In some example embodiments, the magnets 366 may becomprised of NdFeB N42 material, have a diameter of substantially 0.750″and a thickness of substantially 0.125″, with a magnetic field strengthof substantially 13,200 Gauss/3,240 surface field Gauss oriented in adirection substantially normal to the plane of the rotor 362. In someexample embodiments, the magnets 366 may be electromagnets. In someexample embodiments, the total number of magnets 366 disposed on eachside of the rotor 362 may be 48.

In some example embodiments, the rotor 362 may be comprised of amagnetic material having a corresponding magnetic pole orientationsubstantially normal to the plane of the rotor 362, obviating the use ofrecesses 365 and discrete magnets 366 for mounting in the recesses 365.

In some example embodiments, the rotor 362 acts merely as a conductorand the surrounding pulley plate 351 or back cover 361 or both ismagnetized, for example, by introduction of recesses 365 andcorresponding magnets 366 in their facing surfaces. In such exampleembodiments, the materials out of which the rotor 362 and the pulleyplate 351 or the back cover 361 or both may be reversed.

The brake 360 thus imparts a braking force to the travel of the cableloop 131 around the pulleys 352, 223 of the brake 360 and receiver 120.In some example embodiments, the rotation of the drive pulley 352 fromtravel of the cable loop 131 around it causes the transverse axle 354passing through the drive pulley 352 in fixed rotational engagementtherewith to rotate, thus causing the rotor 362 mounted on the axle 354on the opposite side of the pulley plate 351 to rotate relative to thepulley plate 351 or the back cover 361 or both. A magnetic fieldimparted between the rotor 362 and the pulley plate 351 or back cover361 or both, creates eddy currents that oppose the rotation of the rotor362 and impart a braking force on the rotor 362. This force istransmitted by the transverse axle 354 to slow the rotation of the drivepulley 352 and thus to slow the travel of the cable loop 131 around thedrive pulley 352, which slows the descent of the carriage 140 and itssupported load in a controlled fashion.

With reference again to FIG. 2, the cable 130 may in some exampleembodiments comprise a small eyelet 132 at each end to permit the endsof the cable 130 to be joined together to form a cable loop 131. In someexample embodiments, the cable eyelets 132 may be fastened together. Insome example embodiments, the carriage 140 may be positioned proximateto one of the cable eyelets 132 at one end of the cable 130 andconstrained to remain in this position by a cable clamp 133 fixed to thecable 130 so that the carriage 140 lies within a small space between thecable clamp 133 and the cable eye 132. In some example embodiments, thecarriage 140 may be fastened to the cable eyelets 132 directly,obviating the cable clamp 133.

The carriage 140 may be engaged in a ready position by the receiver 110proximate to the structure 10 to provide a mechanism for rapid egressfrom the structure 10 for personnel or equipment or both. In someexample embodiments, the carriage 140 may be released by attaching tothe carriage 140 a load (not shown), such as personnel or equipment orboth, that exceeds the gripping force of the magnet 233.

In some example embodiments, the carriage 140 may comprise a T-handle141 or other structure that may be grasped by a worker on the structure10 such as a sitting shuttle (not shown) or a standing shuttle (notshown). Imparting a load, such as by a worker grasping the T-handle 141,on the carriage forces the carriage 140 to disengage from the receiver110 and to descend with the load along a path defined by the cable loop131 to the ground surface 20 proximate to the brake assembly 120.

Once the carriage 140 and its supported load have reached the brakeassembly 120, the load may be disengaged from the carriage 140 and thecarriage 140 may be moved upward toward the receiver 110 by driving thecable loop 131 to travel in the opposite direction. In some exampleembodiments, this may be facilitated by mounting a rotatable wheelcrank628 (FIG. 6) on the transverse axle 354 or other suitable reloadingmechanism.

The carriage 140 may be seen to engage the cable loop 131 at two places144, 145, respectively on the downstream (top) 134 and upstream (bottom)135 portions of the cable loop 131. The carriage 140 is constrained tolie proximate to the cable eyelets 132, which are joined together toform the cable loop 131, at the first place 144 on the downstreamportion 134, by the imposition of the cable clamp 133 on the other sideof the carriage 140. The upstream portion 135 of the cable loop 131passes through and is free to move relative to the carriage 140 at thesecond place 145, which lies substantially vertically below the firstplace 144 on the downstream portion 134 of the cable loop 131 when thesystem 100 is mounted and operational.

A cover (not shown) hinged at one side (in the FIG. 2, the top side)provides internal access to the carriage 140, for maintenance purposesand to provide access for inserting both portions 144, 145 of the cableloop 131 within the carriage 140. The cover may be secured by a centralbolt and nut (not shown) and or a secondary safety latch and/or a hingepin (not shown) inserted through the carriage 140 and bottom side of thecover or both.

A metal spigot 146 extends out of the top of the carriage 140 and isadapted to engage the magnet 233 housed in the receiver seat 224. Themagnetic force between the magnet 233 and the spigot 146 maintain thecarriage 140 in a ready position proximate to the receiver 110 until adownward load is applied to the carriage 140, such as by a workergripping the T-handle 141 and exiting the structure 10, which exceedsthe gripping force of the magnet 233.

In some example embodiments, a lever (not shown) provides a secondarybraking capability which may be employed by a worker suspended from theT-handle 141.

The downstream portion 134 of the cable loop 131 is tucked near the topof the carriage 140, by the hinge. It is constrained in position by thecable eyelets 132 on one side and the cable clamp 133 or swedge (notshown) on the other. The upstream portion 135 of the cable loop 131 istucked between a secondary brake pad 147 and a freely rotating sheave148. Unless the secondary brake pad 147 is engaged by pulling on thelever, to which the axle on which the brake pad 147 is mounted isattached, to force the brake pad 147 against the cable loop 131,pinching it between the brake pad 147 and the sheave 148, the upstreamportion 145 of the cable loop 131 is free to move relative to thecarriage 140, guided by the sheave 148.

In operation, from the ready position, the carriage 140 with suspendedload is released from the receiver 110 to descend along the path definedby the downstream portion 134 of the cable loop 131. The drive pulley352, receiver pulley 223 and cable loop 131 define and lie substantiallyin a common plane, taking advantage of the pivoting ability of thereceiver housing 222 relative to the bracket 212.

Descent of the carriage 140 along the cable loop 131 under load impartstraction between the drive pulley 352 and the cable loop 131 travellingwith the carriage 140, which causes rotation of the drive pulley 352,which causes rotation of the transverse axle 354. Rotation of the axle354 causes rotation of both the rotor 362 and the magnets 366 mountedthereon, such as in recesses 365. Rotation of the magnets 366 causes themagnetic field created by the axial polarity of the magnets 366 torotate.

The rotational movement of the magnetic field of the rotor 362 relativeto the pulley plate 351 and back cover 361 comprising the frame induceseddy currents in the frame in a pattern that mirrors that of themagnetic field created by the magnets 366. Because the eddy currents andthe magnetic field mirror each other, they interact to oppose therotation of the magnetic field. This opposition to rotation of themagnetic field translates to a braking force against the rotation of themagnets 366 in the rotor 362, against the rotation of the axle 354 andagainst the rotation of the drive pulley 352, slowing the descent of thecarriage 140 and suspended load travelling along the cable loop 131.Consequently, the carriage 140 and suspended load make their descentalong the path defined by the downstream portion 134 of the cable loop131 at a controlled rate.

The brake 360 operates passively in braking the cable loop 131 in thatthere is no applied power or control to operate it. Rather, the rotationof the rotor 362 creates a traveling wave magnetic field relative to theconductive frame. During rotation, the traveling wave magnetic field isin motion relative to a conducting medium such as the frame. Therelative motion of this wave induces eddy currents in the conductivemedium in a pattern which mirrors that of the driving field. The inducededdy currents interact with the field of the magnets 366 to develop abraking force. As long as the magnets 366 remain magnetized and relativemotion is developed between the magnets 366 and the frame, a brakingforce is generated. The braking force is a function of the relativestrengths of one or more of the magnets 366, and induced currents andtheir relative phase offsets. The magnitude and phase offset of theinduced current may vary as a function of the relative wave velocity,magnetic field strengths, wavelength of the field and conductorresisitivity.

The strength of the braking force may be proportional to the distancebetween the rotor 362 and the frame and the thickness of the frame. Thebraking force may be controlled by adding or removing magnets 366,changing the spacing between the pulley plate 351 and rotor 362,changing the spacing between the back cover 361 and rotor 362, changingthe diameter of the pulley plate 351, back cover 361 or rotor 362 or anycombination of them, changing the type or strength of the magnets 366;changing the material from which the pulley plate 351, back cover 361,rotor 362, magnets 366 or any combination of them are composed or withwhich they are cladded or inserted, or changing the number of rotor 361and frame pairs on the transverse axle 354. In some experiments,machining the pulley plate 351 and back cover 361 to include a 3/16″copper plate resulted in an increase in braking power of at least around40%.

Because the strength of the eddy currents may be proportional to thevelocity of the rotor 362 relative to the stationary frames, as the rateof descent of the carriage 140 increases, the braking force increases.Similarly, decreasing the rate of descent of the carriage 140 decreasesthe braking force. This proportionality produces a relatively smootherdeceleration and allows the carriage 140 to descend in a controlledmanner towards the terminal point (not shown), resulting in a relativelygentler landing. Rates of descent of about 14 ft/s (peak at around 22ft/s) have been experienced for descents from high elevations, whilemore moderate descent elevations result in rates of descent of about 7-8ft/s and landing speeds as low as 2 ft/s.

The single movable cable loop configuration permits the cable loop 131to take steeper descent paths or descent paths through narrower openingsbetween obstacles.

In some example embodiments, including the embodiments described herein,the brake 360 employs the eddy current brake described in FIGS. 8 and 9.In some example embodiments, adequate performance may be obtained byusing other conventional brake mechanisms, including disk, drum andcable braking mechanisms in substitution for the eddy current brakedescribed in FIGS. 8 and 9.

As well, the disclosed system 100 is easier to configure, transport,install, move and store away. In some example embodiments, the system100 may comprise a kit.

While the present disclosure is sometimes described in terms of methods,the present disclosure may be understood to be also directed to variousapparata including components for performing at least some of theaspects and features of the described methods, be it by way of hardwarecomponents or combinations thereof, or in any other manner. Suchapparata and articles of manufacture also come within the scope of thepresent disclosure.

The various embodiments presented herein are merely examples and are inno way meant to limit the scope of this disclosure. Variations of theinnovations described herein will become apparent from consideration ofthis disclosure and such variations are within the intended scope of thepresent disclosure.

For example, the magnets 366 could be mounted in the pulley plate 351 orthe back cover 361 or both and the eddy currents could be formed in therotor 362.

Other embodiments consistent with the present disclosure will becomeapparent from consideration of this specification and the practice ofthe disclosure set out therein.

According to a first broad aspect of the present disclosure, there isdisclosed a descent system for controlling movement of a load between aninitial point and a terminal point, the system comprising: a cableformed into a loop; a receiver having a receiver pulley for engaging thecable loop around it at the initial point; a brake assembly having adrive pulley for engaging and being rotated by the cable loop at theterminal point, the brake assembly for slowing the rate of travel of thecable loop around the pulleys; and a carriage secured to the cable forsupporting the load and for movement between the initial point and theterminal point as the cable loop travels around the pulleys.

According to a second brad aspect of the present disclosure, there isdisclosed a brake assembly for use in a descent system for controllingmovement of a load between an initial high point and a terminal lowpoint, the system comprising a cable formed into a loop, a receiverhaving a receiver pulley for engaging the cable loop around it at theinitial point and a carriage secured to the cable for supporting theload, the brake assembly having a drive pulley for engaging and beingrotated by the cable loop at the terminal point, the brake assembly forslowing the rate of travel of the cable loop around the pulleys.

According to a third brad aspect of the present disclosure, there isdisclosed a kit comprising: a cable for forming into a loop; a receiverhaving a receiver pulley for engaging the cable loop around it at aninitial point; a brake assembly having a drive pulley for engaging andbeing rotated by the cable loop at a terminal point, the brake assemblyfor slowing a rate of travel of the cable loop around the pulleys; and acarriage for securing to the cable and for supporting a load formovement between the initial point and the terminal point as the cableloop travels around the pulleys.

Accordingly the specification and the embodiments disclosed therein areto be considered examples only, with a true scope and spirit of thedisclosure being disclosed by the following numbered claims:

The invention claimed is:
 1. A descent system for controlling movementof a load between an initial point and a terminal point, the systemcomprising: a cable formed into a loop; a receiver having a receiverpulley for engaging the cable loop around it at the initial point; abrake assembly having a drive pulley for engaging and being rotated bythe cable loop at the terminal point, the brake assembly for slowing therate of travel of the cable loop around the pulleys, the brake assemblycomprising an axle in fixed rotational engagement with the drive pulley,a substantially planar ferromagnetic rotor in fixed rotationalengagement with the axle, the rotor comprising at least one recessformed in a surface thereof, and at least one permanent magnet fixedlydisposed within the recess, and at least one conducting frame elementdisposed proximate to the rotor whereby an eddy current may be inducedby rotational movement of the rotor relative to the at least oneconducting frame element in a direction to oppose acceleration of thedrive pulley as it is rotated by the cable loop; and a carriage securedto the cable for supporting the load and for movement between theinitial point and the terminal point as the cable loop travels aroundthe pulleys.
 2. The descent system according to claim 1, wherein thecable has an eyelet at each end of the cable, the eyelets being securedtogether to form the cable loop.
 3. The descent system according toclaim 1, wherein the carriage is secured to the cable proximate to oneend of the cable.
 4. The descent system according to claim 1, whereinthe carriage is secured to the cable between one end of the cable and aclamp on the cable.
 5. The descent system according to claim 1, whereinthe receiver is secured to a structure at the initial point.
 6. Thedescent system according to claim 5, wherein the receiver is secured tothe structure by a receiver mount.
 7. The descent system according toclaim 1, wherein the receiver comprises a seat for retaining thecarriage in a ready position proximate to the structure.
 8. The descentsystem according to claim 7, wherein the receiver seat comprises amagnet for gripping the carriage.
 9. The descent system according toclaim 7, wherein application of the load to the carriage releases thecarriage from the seat and commences travel of the carriage toward theterminal point.
 10. The descent system according to claim 1, wherein therotor is maintained parallel with the drive pulley, and the rotor ismaintained substantially perpendicular to the axle.
 11. The descentsystem according to claim 1, wherein the at least one fixed magnet isdisposed in the at least one recess of the rotor facing one of thecorresponding at least one frame elements.
 12. The descent systemaccording to claim 1, wherein the drive pulley comprises a plurality ofcoaxial pulleys of different diameter for engaging the cable loop. 13.The descent system according to claim 1, wherein the carriage comprisesa secondary brake for slowing the rate of travel of the cable looparound the pulleys.
 14. A kit comprising: a cable for forming into aloop; a receiver having a receiver pulley for engaging the cable looparound it at an initial point; a brake assembly having a drive pulleyfor engaging and being rotated by the cable loop at a terminal point,the brake assembly for slowing a rate of travel of the cable loop aroundthe pulleys, the brake assembly comprising an axle in fixed rotationalengagement with the drive pulley, a substantially planar ferromagneticrotor in fixed rotational engagement with the axle, the rotor comprisingat least one recess formed in a surface thereof, and at least onepermanent magnet fixedly disposed within the recess, and at least oneconducting frame element disposed proximate to the rotor whereby an eddycurrent may be induced by rotational movement of the rotor relative tothe at least one conducting frame element in a direction to opposeacceleration of the drive pulley as it is rotated by the cable loop; anda carriage for securing to the cable and for supporting a load formovement between the initial point and the terminal point as the cableloop travels around the pulleys.
 15. The kit according to claim 14,further comprising a receiver mount for securing the receiver to astructure at the initial point.